A photoelectric conversion device includes a common output line, a sensor cell unit which outputs a signal to the common output line, a transfer circuit unit which is connected to the common output line, holds a signal from the common output line in a transfer capacitor, and transfers the signal, first, second and third memory cell units each of which stores a signal from the common output line in a memory capacitor, inverts and amplifies the signal in the memory capacitor, and outputs the signal to the common output line.
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1. A photoelectric conversion device comprising: a common output line; a sensor cell unit which outputs a signal photoelectrically converted by a photoelectric converter to the common output line; a transfer circuit unit which is connected to the common output line, holds a signal from the common output line in a transfer capacitor, and transfers the signal; a first memory cell unit which is connected to the common output line, stores a signal from the common output line in a first memory capacitor, inverts and amplifies the signal in the first memory capacitor, and outputs the signal to the common output line; a second memory cell unit which is connected to the common output line, stores a signal from the common output line in a second memory capacitor, inverts and amplifies the signal in the second memory capacitor, and outputs the signal to the common output line; and a third memory cell unit which is connected to the common output line, stores a signal from the common output line in a third memory capacitor, inverts and amplifies the signal in the third memory capacitor, and outputs the signal to the common output line, wherein the first memory cell unit writes, in the first memory capacitor, a reset noise signal originating from resetting of the photoelectric converter, the transfer capacitor, the first memory capacitor, the second memory capacitor, and the third memory capacitor, the third memory cell unit writes, in the third memory capacitor, a reset noise signal obtained by making the first memory cell unit invert and amplify a reset noise signal written in the first memory capacitor, the second memory cell unit writes, in the second memory capacitor, a reset noise signal obtained by making the third memory cell unit invert and amplify a reset noise signal written in the third memory capacitor, and the transfer circuit unit writes, in the transfer capacitor, a signal obtained by adding a signal obtained by making the second memory cell unit invert and amplify a reset noise signal written in the second memory capacitor to a signal output from the sensor cell unit.
A photoelectric conversion device captures light and converts it to electrical signals. It has a common output line, a sensor cell that sends a photo-converted signal to this line, and a transfer circuit. The transfer circuit captures and holds the signal from the output line in a capacitor, and then transfers it elsewhere. The device also includes three memory cells. Each cell stores the common output line signal in its own capacitor, inverts and amplifies the signal, and sends it back to the output line. The first memory cell stores reset noise from the photoelectric converter and various capacitors. The third cell stores an inverted and amplified version of the first cell's noise. The second cell stores an inverted and amplified version of the third cell's noise. Finally, the transfer circuit stores a signal that adds the output of the second memory cell to the original sensor cell output.
2. The device according to claim 1 , wherein the sensor cell unit includes a sensitivity switching unit for switching between a low sensitivity mode and a high sensitivity mode, the first memory cell unit writes, in the first memory capacitor, a reset noise signal originating from resetting of the photoelectric converter, the transfer capacitor, the first memory capacitor, the second memory capacitor, and the third memory capacitor in the low sensitivity mode, in the high sensitivity mode, the second memory cell unit and the third memory cell unit write, in the second memory capacitor and the third memory capacitor, a reset noise signal originating from resetting of the photoelectric converter, the transfer capacitor, the first memory capacitor, the second memory capacitor, and the third memory capacitor, and in the low sensitivity mode, the third memory cell unit writes, in the third memory capacitor, a reset noise signal obtained by making the first memory cell unit invert and amplify a reset noise signal written in the first memory capacitor, and the second memory cell unit then writes, in the second memory capacitor, a reset noise signal obtained by making the third memory cell unit invert and amplify a reset noise signal written in the third memory capacitor.
The photoelectric conversion device from the previous description includes a sensor cell with adjustable sensitivity (high or low). In low sensitivity mode, the first memory cell stores reset noise. The second and third cells only store reset noise in high sensitivity mode. Still in low sensitivity mode, the third memory cell stores an inverted, amplified version of the first memory cell's noise, and then the second memory cell stores an inverted, amplified version of the third memory cell’s noise. This allows for noise correction depending on the sensitivity mode.
3. The device according to claim 1 , wherein the first memory cell unit, the second memory cell unit, and the third memory cell unit each has an amplification gain of −1.
The photoelectric conversion device from the initial description has three memory cells, and each of these memory cells (first, second, and third) inverts and amplifies the signal with a gain of -1. This means each memory cell flips the sign of the signal and maintains the original magnitude of the signal.
4. The device according to claim 1 , wherein the second memory cell unit writes, in the second memory capacitor, an addition signal written in the transfer capacitor of the transfer circuit unit.
The photoelectric conversion device from the initial description includes a second memory cell that stores in its memory capacitor a signal that was previously written to the transfer capacitor of the transfer circuit. Essentially, the content of the transfer capacitor is copied to the second memory cell.
5. A camera system comprising: a photoelectric conversion device defined in claim 1 ; and a lens for forming an optical image on the photoelectric conversion device.
A camera system includes a photoelectric conversion device and a lens. The photoelectric conversion device has a common output line, a sensor cell that sends a photo-converted signal to this line, and a transfer circuit. The transfer circuit captures and holds the signal from the output line in a capacitor, and then transfers it elsewhere. The device also includes three memory cells. Each cell stores the common output line signal in its own capacitor, inverts and amplifies the signal, and sends it back to the output line. The first memory cell stores reset noise, and then that noise is processed through the other memory cells for noise reduction. The lens focuses light onto the photoelectric conversion device to create an image.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
November 22, 2011
August 6, 2013
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